/**
 * 每个位置枚举一下即可
 */
#include <bits/stdc++.h>
#include <bits/extc++.h>
using namespace std;


using llt = long long;
using vi = vector<int>;
using vll = vector<llt>;
using pll = pair<llt, llt>;

llt const INF = 0x7F1F2F3F4F5F6F7F;

int N;
int M;

bool proc(){
    int flag = 0;
    for(int i=0;i<N;++i){
        string s; cin >> s;
        if(i + 1 == N) return true;
        
        if("sweet" == s){
            if(flag == 1) return false;
            flag = 1;
        }else{
            flag = 0;
        }
    }
    return true;
}

void work(){ 
    cin >> N;
    cout << (proc() ? "Yes\n" : "No\n");
	return;
}

int main(){
#ifndef ONLINE_JUDGE
    freopen("z.txt", "r", stdin);
#endif
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);	
    int nofkase = 1;
	// cin >> nofkase;
	while(nofkase--) work();
	return 0;
}